1. Objective This study aimed to find out the epidemiologic characteristics of constitutional disease syndromes at a hospital of Oriental medicine in Seoul. 2. Methods The medical records of 1354 subjects who have received prescriptions and diagnosis of Sasang constitution from January 2008 to December 2009 at a hospital of Oriental medicine were reviewed. General factors and the frequency of the prescriptions according to Sasang constitution were compared and analyzed. 3. Results 1) Among the 1354 subjects, 562(41.5%) persons were males and 792(58.5%) females. 614(45.3%) persons were Soeumin, 369(27.3%) Soyangin, 364(26.9%) Taeumin, and 7(0.5%) Taeyangin. 2) The frequencies of the prescriptions of 14 constitutional disease syndromes were compared. Taeum Syndrome, Esophagus Cold Syndrome and Yin Deficiency Tidal fever Syndrome show the high frequencies among 14 disease syndromes. Chest Heat Syndrome, Deficiency of Yin and Blood syndrome and Soeum Syndrome show the low frequencies among 14 disease syndromes. Interior disease(63.4%) was higher than exterior disease(36.6%) and mild disease(61.8%) was higher than severe disease(38.2%). 3) Among all constitutional prescriptions, Jowyiseungchung-tang was the most common and next rankings were Gupoong-tang and Dokhwaljihwang-tang in turns. 4. Conclusions From all these considerations, it would seem that Taeum Syndrome in Soeumin, Esophagus Cold Syndrome in Taeumin and Yin Deficiency Tidal fever Syndrome in Soyangin show the high frequencies in a hospital of Oriental medicine in Seoul. Large-scale epidemiologic study in Sasang constitutional medicine may be needed on various ways and places.